The video below shows the steps in my process to create a rectangular bonsai pot from clay slab. All of my work is made from pure craftsmanship without the use of forms or molds. In the article below I outline the process I use throughout the video.
I start only with high quality, commercially prepared stoneware clay that I have cured over 8-10 hours on a canvas wrapped board. Repeatedly during this time it is compressed by slab roller and by hand using a rubber tool which helps to later prevent cracking and warping.
The slab is then hand cut using a template which is drawn to the desired dimensions. The dimensions for the template are calculated to include approximate clay shrinkage rates.
The corners are mitered using a special tool which ensures the correct angles meet perfectly flush. All edges and joints are scored and coated with clay slurry, a mixture of dried clay mixed with water, which ensures a durable connection.
All of the corners and seams of the bonsai pot are reinforced with a clay bead which provides extra strength and ensures all joints are fully sealed. This technique also creates a subtle inner curve inside the pot which assists with proper water drainage.
Feet are attached to the bottom of the pot as well as small cubes which are cut to the same height. These small cubes of clay are removed once the piece becomes "leather hard" and prevent the bottom of the pot from sagging during the drying process.
Additional wiring holes are cut at this time and all seams are checked, smoothed and refined.
The profile of the pot is checked and any imperfections are corrected while the piece remains soft. The bonsai pot is then wrapped loosely with plastic sheet and stored in a cool, controlled environment to dry slowly over a period of one or several weeks depending on the size.
A slow drying process is extremely important to prevent cracking. The piece can then be fired and, if desired, glazed.